当同塔四回线遇上极端情况,发生断线故障,甚至跨线间断线,复杂的线路耦合给故障分析带来困难,研究断线故障分析方法,有利于完善继电保护配置.根据四回线阻抗分布情况,利用12序分量法解耦,基于断线故障特点,重新定义故障序网图和综合电动势.化简断线故障边界条件方程组后得到简化的序分量关系,当电压或电流约束方程只有1个时,可通过修正序阻抗系数,构建复合序网图.通过复合序网图,可以巧妙地将复杂的方程组转化为简单的图形网络,快速计算故障量.而如果电压或电流约束方程不止1个时,复合序网图无法统一,可通过解方程组的方法计算各序分量.PSCAD(power systems computer aided design)仿真结果表明,复合序网图应用于单回线断线故障分析具有可行性,而复杂断线情况下,利用解方程组法可实现故障分析.
Disconnection fault analysis method of four-parallel lines on the same tower
When the four-parallel lines on the same tower encounter extreme conditions,such as disconnection faults,even disconnections across lines,the complex line coupling brings difficulties to the fault analysis.The research on disconnection fault analysis methods is conducive to perfecting the relay protection configuration.According to the impedance distribution of four-parallel lines,the 12-sequence component method was used to decouple,fault sequence network diagram and comprehensive electromotive force were redefined based on the characteristics of disconnection fault.The simplified sequence component relationship was obtained by simplifying the boundary condition equations of disconnection faults.If there is only one constraint equation of voltage or current,the composite sequence network is constructed by modifying the sequence impedance coefficient.Through the composite sequence network,the complex equations can be skillfully transformed into a simple graphical network,the fault quantity can be calculated quickly.If there is more than one constraint equation of voltage or current,the composite sequence network cannot be unified,the sequence components can be calculated by the method of solving the equations.Power system computer aided design(PSCAD)simulation results show that it is feasible to apply the composite sequence network to single-circuit line disconnection fault analysis,while in the case of complex disconnection,the fault analysis can be realized by solving equations.
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